1. Field Of The Invention
The present invention relates to phosphoric acid esters of oxetanocins having an antiviral activity which are represented by general formula (I): ##STR2## wherein R.sub.1 represents a phosphoric acid ester residue, X represents hydrogen, hydroxy or hydroxymethyl group, and B represents a purine base residue, and pharmacologically acceptable salts thereof.
2. Description Of The Prior Art
Oxetanocin itself is disclosed in Journal of Antibiotics, Vol. 39, No. 11, Pages 1623-25 (1986), EP-A.sub.2 -0 182 312, etc.
The derivatives thereof are described in Journal of Antibiotics, Vol. 40, No. 12, page 1788-90 (1987), EP-A-0 291 917 and EP-A-0 334 250.
It is also known in view of the publications described above that these compounds exhibit an antiviral activity.
At the present time, however, no satisfactory therapeutic drug is available for viral diseases It is thus desired to develop a novel antiviral agent.